1. Field of the Invention
The present invention generally relates to an automatic blood pressure measuring apparatus, and particularly to such an apparatus which measures blood pressure of a subject based on Korotkoff sounds produced from an arterial vessel of the subject.
2. Discussion of the Prior Art
There is known an automatic blood pressure measuring instrument which includes (a) an inflatable cuff having an elongate configuration, the inflatable cuff being wound around a body portion of a subject, for pressing an arterial vessel of the subject via a body surface over the arterial vessel, (b) a detector such as a microphone, for detecting at least one Korotkoff sound produced from the arterial vessel as the pressing force of the inflatable cuff applied to the arterial vessel is varied, and determining system for determining at least one blood pressure value of the subject based on the detected at least one Korotkoff sound.
In the above-indicated conventional instrument, the microphone or other Korotkoff sounds detector is positioned in a distal end area of the cuff which area is more remote from the heart of the subject than the other, proximal end area of the cuff. Accordingly, for example in the event that the subject is in a condition of shock and his or her pulsation is not strong enough, it has conventionally been experienced that the microphone cannot detect Korotkoff sounds with sufficiently great magnitudes, and therefore that accurate blood pressure measurement is difficult.